Safe geometry nuclear fuel powder blender

ABSTRACT

A safe geometry nuclear fuel powder blender of a tumble type having unique and improved concepts of loading and unloading, powder mixing pins, access hatches, and drive means. The powder is fluidized by an appropriate gas and subjected to a rocking motion to facilitate flow to a discharge mechanism of a vacuum pickup or screw conveyor type. Structural integrity and safe and easy operating access hatches are provided.

1 July 23,1974

2,514,375 7/1950 Cornell..............,.................. 259/89 SAFEGEOMETRY NUCLEAR FUEL POWDER BLENDER [75] Inventors: James A. Frye,Oklahoma City;

FOREIGN PATENTS OR APPLICATIONS 4/1965 Germany 259/3 Ralph B. Morton,Del City, both of Okla.

[73] Assignee: The Boardman Company,

Primary Examiner-Peter Feldman Oklahoma City, Okla. AssistantExaminer-Philip R. Coe May 4, 1972 [21] Appl. No.: 250,130

[22] Filed:

ABSTRACT A safe geometry nuclear fuel powder blender of a tumble typehaving unique and improved concepts of loading and unloading, powdermixing pins, access hatches, and drive means. The powder is fluidized byan appropriate gas and subjected to a rocking motion to facilitate flowto a discharge mechanism of a vacuum pickup or screw conveyor type.Structural integrity and safe and easy operating access hatches areprovided.

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[56] References Cited UNITED STATES PATENTS 2,100,599 11/1937 Schulthesset 259/30 X 10 Claims, 10 Drawing Figures PATENTEDJULZSIBH SHEET 2 BF 3BLEN DED

MATERIAL BLENDED MATERIAL AIR M SOURC i PATENIED JULZBIQM sum 3 or 3SAFE GEOMETRY NUCLEAR FUEL POWDER BLENDER BACKGROUND OF THE INVENTION vSUMMARY1OF THE INVENTION The present invention generally relates to atumble type nuclear fuel powder blender and, more especially, to adesign and method of loading and unloading the blender, design of mixingpins and access hatches, and

method of driving the unit. In one concept, unloading of the materialafter blending is performed pneumatically with dry air or inert gaswhich is injected into an air chamber surrounding the bottom half of theblender drum which functions to fluidi'ze the powder and, aided by arocking motion, the material is caused to flow into a vacuum pickup forconveying to a subsequent station. A specifically different form ofdischarge includes a variable pitch screw conveyor, which permitsgreatly reducing rocking and vibration and injection of gas tosubstantially reduce problems of dusting and overpressure in theblender.

Mixing pins within the blending chamber serve structurally as stay boltsfor structural integrity in the event of excessive pressure buildup andothers of the pins act to prevent collapsing during a vacuum loadingcycle.

A hatch construction is provided having features facilitating ease ofmanufacture, provision of a bimetallic construction and improved sealingand release characteristics.

Additional objects, advantages and features of the invention will bemore readily apparent from the following detailed description ofembodiments thereof when taken together with the accompanying drawingsin which:

FIG. 1 is a front elevational view of an embodiment of the invention,including rotating drive means and a schematic illustration of airflotation and conveying means;

FIG. 2 is an enlarged, detailed vertical sectional view taken on line 22of FIG. 1;

FIG. 3 is an enlarged, detailed, fragmentary sectional view along line33 of FIG. 2;

FIG. 4 is an enlarged, fragmentaryvertical sectional view taken alongline 44 of FIG. 3;

FIG. 5 is an enlarged, fragmentary sectional view taken along line 5-5-of FIG. 1, showing mounting of materialflotation implementing air pads;

FIG. 6 is a fragmentary sectional view of a single air pad andassociated mechanism taken along line 6--6 of FIG. 3; V

FIG. 7 is an enlarged, fragmentary elevational view of anaccess hatchshown in FIG. 1;

FIG. 8 is a detailed vertical sectional view taken along line 8-8 ofFIG. 7, disclosing pivoting and locking means for the hatch;

FIG. 9 is a fragmentary elevational view of a modified form of materialdischarge means; and

FIG. 10 is a view similar to FIG. 9 of a still further modification ofdischarge and measured collecting means for blended powder.

Referring now in greater detail to the drawings, the tumble type nuclearfuel powder blender of the invention generally designated 10 includes asubstantially circular drum 12 to which is affixed a removable cover 14by means of bolts and nuts 16 peripherally arranged and spacedthereabout. The design of the blender as shown and described herein wasespecially devised for a 5 inch maximum thickness mixing chamber andsize ranging including various diameter units of, for example, 2 feet, 4feet, 6 feet, 9 feet and 12 feet. The drum is rotatably mounted on abase generally designated 18 by means of shaft 20 joumalled in pillowblock 22, and a driven sprocket 24 operatively attached to the drum 12.A reinforcing gusset 26 interengages hub 28 and sprocket 24. A variablespeed electric motor 30, with reverse drive for rocking motion, isoperatively engaged with sprocket 24 by drive chain 32 in associationwith an idler gear 34. While particularly adapted to impart a rockingmotion to the blender to facilitate material flow to a discharge, thedrive is such that the drum can be rotated as desired and as indicatedby arrow 36.

The drum of the FIG. 1 embodiment is provided with a discharge spout 38opening into a discharge hopper 40 which will be described in greaterdetail hereinafter. Removable cover 14 is provided with a plurality ofaccess hatches 42 spaced therearound, the details of which will bedescribed with reference to FIGS. 7 and 8 and these hatches provideready access to various portions of the blending chamber. A suitablenumber of mixing pins 44 are provided interiorally of the blendingchamber and optionally can be welded in place to the interior of theremovable cover or replaceable and sealed with an O-ring. A suitablenumber of the mixing pins can also act as stay bolts for structuralintegrity in the event of excessive pressure buildup. Others of the pinsact to prevent collapsing of the removable cover during a vacuum loadingcycle. These pins are spaced around the inner periphery of the blendingchamber, or in such other areas as might be indicated, to insure optimumblending of material as the drum rotates during the blending cycle asindicated by arrow 36 in FIG. 1.

As shown in FIGS. 7 and 8, the access hatches 42 are conical for atapered fit with a captured O-ringseal 46. The hatch is made in twoparts divided along the parting line of the O-ring seating groove 47 forease of manufacture and to provide bi-metallic construction. Therelatively thin inner disc 48 is stainless steel for contact with thepowder, while the outer disc 50 is of mild steel and is thicker forstrength. The tapered seat improves opening into the blending chamberand, additionally, a nozzle 66 is provided to facilitate a vacuum hookupand also a vent for excessive fluidizing gas. Unloading is performed inthe embodiment of FIG. 1 pneumatically with dry air or inert gas such asnitrogen being injected into an air chamber 68 which serves as an airpad compartment and in the nature of a plenum chamber. The constructionof the air pads can be as shown in FIG. 6 wherein a coupling half 70 issecured to and opening into the interior of the drum with pad inserts ornozzles 72 having bores 74 therethrough threadedly engaged in thecoupling half. Micron filters 76 are positioned in the bores by snaprings 78. Air from air source 80 passes into and through the nozzles andexits into the interior of the blender drum as indicated by arrows 82with the flow schematically depicted at 82A. As shown in FIG. 5, thenozzles are provided in the pads 72 around the lower half of the drum asa plurality of individualized pads including each of a plurality ofindividual nozzles with air interconnections to the source passingthrough a closure plate 84 for the chamber. Preferably, the dry air padsare valved with quick disconnect couplings. The number of nozzles ineach pad are selected for optimal operation and upon injection of airtherethrough into the interior of the blending drum through the porousmetal filter elements will, in effect, fluidize the powder during ablending cycle of rotation which is aided by the mixing pins. Fluidizingof the powder, aided by a rocking motion induced by motor 30, pluspneumatic vibrators 86, FIG. 4, causes the material to flow into avacuum pickup generally designated 88 as indicated by arrows 90 fortransfer or conveyance to a next station. The vacuum pickup or conveyorhas air introduced therein from an air source through a dry air in quickdisconnect means 92 and blended material as indicated in FIG. 1 isconveyed from the blender, preferably through a quick disconnect plugvalve generally indicated at 94, which provides for a quick disconnectand additionally serves to prevent air inlet into the chamber duringhookup and disconnect. Excess fluidizing gas is vented through thenozzle on the top of the drum and can be filtered by the same vacuumunit used to load the unit when a vacuum is applied to nozzle 66 andpowder is introduced through inlet 64.

Specifically different mechanism for unloading the unit is shown in FIG.9, wherein material flows through discharge outlet 96 into a dischargehopper 98 in which is mounted a screw conveyor 100, having a variablepitch flight and rotatably driven by hydraulic motor 102 from a powersource generally designated 104. A discharge spout 106 is arranged atthe exit end of the screw conveyor and the material is again conveyed byair entering through air disconnect means 92 and exiting a plug valve 94similar to the previous arrangement. In one embodiment, a 4 inchdiameter variable pitch screw conveyor is used powered by a low speed,high torque hydraulic motor. The hoses disconnect during the blendingcycle and are attached for unloading.

. Rocking and vibration will be greatly reduced and injection of gas andresulting problems of dusting and over-pressure are virtuallyeliminated.

FIG. is similar in concept to the mechanism of FIG. 9, but furtherincludes a container filling concept. The material handling container108, provided by a customer, is inserted in a closed dust-tightenclosure generally indicated at 110, manually mounted by manualconnector means 112 of any suitable type, and which are detachedtherefrom and removed during the blending cycle.

Air cylinders 114 are incorporated in enclosure to lift container 108into compressed engagement with an elastomeric material indicated at109, provided on the discharge spout to provide a seal during discharge.Nuclear level indicator/controller means generally indicated at 116 areprovided which function to opera tively transmit a signal to hydraulicmotor 102 of the hydraulic unloading system for control of material flowinto the container 108 in a manner similar to the embodiment of FIG. 9.

The basic function and operation of the embodiments of FIGS. 1, 9 and 10are substantially the same. The specifically different dischargemechanisms are optionally usable. The blender is loaded by pulling ahard vacuum on the chamber and conveying powder into it through propernozzles. Tubing plug valves as hereinbefore referred to are recommendedfor sealing against the atmosphere while changing connections.

Manifestly, minor changes can be effected in details without departingfrom the spirit and scope of the invention as defined in and limitedsolely by the appended claims.

We claim:

I. A nuclear fuel powder blender comprising:

A. a rotatable closed cylindrical blending chamber consisting of a drum;

B. power blending means operably associated with said beldning chamber;

c. drive means for said chamber operable to selectively rotate and rocksaid chamber for a blending cycle and facilitating discharge of blendedpowder fromsaid chamber respectively;

D. blended powder discharge outlet from said chamber; and

E. blended powder unloading means operatively opening into saiddischarge outlet for conveying blended powder from said blender,including means for injecting air under pressure into the bottom half ofsaid drum to fluidize powder therein, the fluidizing in conjunction withrocking said drum causing material to flow to said discharge outlet.

2. A nuclear fuel powder blender as claimed in claim 1, including an airchamber surrounding the bottom half of said drum, a plurality of airinjector pads in said chamber spaced peripherally around said bottomhalf of said drum, porous metal filter elements interposed between saidair pads and the interior of said drum, said unloading means including avacuum pickup positioned below said discharge outlet and adapted toconvey blended powder to a subsequent station.

3. A nuclear fuel powder blender as claimed in claim 2, wherein saiddrum includes a venting nozzle on the top thereof, excess fluidizing gasbeing vented through said nozzle, a vacuum loading unit in said drum,said vented fluidizing gas being filtered by said vacuum unit.

4. A nuclear fuel powder blender as claimed in claim 1, said unloadingmeans including a variable pitch screw conveyor positioned below saidblended powder discharge outlet, an air injection means operativelyassociated with the discharge end of said screw conveyor to entrain andconvey blended powder discharged therefrom, and a vacuum pickup forconveying the powder to a subsequent station.

5. A nuclear fuel powder blender as claimed in claim 1, said unloadingmeans including a variable pitch screw conveyor to receive and impelpowder to a discharge outlet therefrom, a material handling containerremovably positioned below the discharge outlet from said screw conveyorand nuclear level controller means associated with said container forcontrol of the screw conveyor for determining the amount of powderdischarged into said container.

6. A nuclear fuel powder blder as claimed in claim 5, including a dusttight enclosure for confining said container, elastomeric sealing meansbetween said container and the discharge from said screw conveyor, meansoperable to force the mouth of said container into sealing engagementwith said discharge outlet, said dust tight enclosure and said containerbeing removed during the powder blending cycle.

7. A nuclear fuel powder blender as claimed in claim 1, said blendingchamber comprising a circular, openfaced drum, a removable cover forsaid drum, a plurality of mixing pins attached to the interior of saidremovable cover, some said mixing pins acting as stay bolts forstructural integrity in the event of excessive pressure buildup in saiddrum, and others of said pins acting to prevent collapsing of theremovable cover during a vacuum loading cycle.

8. A nuclear fuel powder blender as claimed in claim 7, including meansfor pulling a hard vacuum on said chamber and means for conveying powderinto said chamber through nozzles associated therewith and tubing plugvalves associated with the vacuum and powder conveying mechanism forsealing against the atmosphere while changing connections betweenloading, blending and discharge cycles.

9. A nuclear fuel powder blender as claimed in claim 1, said blendingchamber comprising a circular openfaced drum, a removable cover for saiddrum, a hatch on said cover mounted for pivotal movement to open andclosed positions, said hatch when open providing access to the interiorof said drum.

10. A nuclear fuel powder blender as claimed in claim 9, said hatchbeing conical, a captured O-ring seal adapted for tapered fitting withsaid conical hatch, said hatch consisting in two parts divided along theparting line of a seating groove for said O-ring, said partsconstituting a bimetallic hatch construction, and quick opening hatchdogs for said hatch.

1. A nuclear fuel powder blender comprising: A. a rotatable closedcylindrical blending chamber consisting of a drum; B. power blendingmeans operably associated with said beldning chamber; c. drive means forsaid chamber operable to selectively rotate and rock said chamber for ablending cycle and facilitating discharge of blended powder from saidchamber respectively; D. blended powder discharge outlet from saidchamber; and E. blended powder unloading means operatively opening intosaid discharge outlet for conveying blended powder from said blender,including means for injecting air under pressure into the bottom half ofsaid drum to fluidize powder therein, the fluidizing in conjunction withrocking said drum causing material to flow to said discharge outlet. 2.A nuclear fuel powder blender as claimed in claim 1, including an airchamber surrounding the bottom half of said drum, a plurality of airinjector pads in said chamber spaced peripherally around said bottomhalf of said drum, porous metal filter elements interposed between saidair pads and the interior of said drum, said unloading means including avacuum pickup positioned below said discharge outlet and adapted toconvey blended powder to a subsequent station.
 3. A nuclear fuel powderblender as claimed in claim 2, wherein said drum includes a ventingnozzle on the top thereof, excess fluidizing gas being vented throughsaid nozzle, a vacuum loading unit in said drum, said vented fluidizinggas being filtered by said vacuum unit.
 4. A nuclear fuel powder blenderas claimed in claim 1, said unloading means including a variable pitchscrew conveyor positioned below said blended powder discharge outlet, anair injection means operatively associated with the discharge end ofsaid screw conveyor to entrain and convey blended powder dischargedtherefrom, and a vacuum pickup for conveying the powder to a subsequentstation.
 5. A nuclear fuel powder blender as claimed in claim 1, saidunloading means including a variable pitch screw conveyor to receive andimpel powder to a discharge outlet therefrom, a material handlingcontainer removably positioned below the discharge outlet from saidscrew conveyor and nuclear level controller means associated with saidcontainer for control of the screw conveyor for determining the amountof powder discharged into said container.
 6. A nuclear fuel powder blderas claimed in claim 5, including a dust tight enclosure for confiningsaid container, elastomeric sealing means between said container and thedischarge from said screw conveyor, means operable to force the mouth ofsaid container into sealing engagement with said discharge outlet, saiddust tight enclosure and said container being removed during the powderblending cycle.
 7. A nuclear fuel powder blender as claimed in claim 1,said blending chamber comprising a circular, open-faced drum, aremovable cover for said drum, a plurality of mixing pins attached tothe interior of said removable cover, some said mixing pins acting asstay bolts for structural integrity in the event of excessive pressurebuildup in said drum, and others of said pins acting to preventcollapsing of the removable cover during a vacuum loading cycle.
 8. Anuclear fuel powder blender as claimed in claim 7, including means forpulling a hard vacuum on said chamber and means for conveying powderinto said chamber through nozzles associated therewith and tubing plugvalves associated with the vacuum and powder conveying mechanism forsealing against the atmosphere while changing connections betweenloading, blending and discharge cycles.
 9. A nuclear fuel poWder blenderas claimed in claim 1, said blending chamber comprising a circularopen-faced drum, a removable cover for said drum, a hatch on said covermounted for pivotal movement to open and closed positions, said hatchwhen open providing access to the interior of said drum.
 10. A nuclearfuel powder blender as claimed in claim 9, said hatch being conical, acaptured O-ring seal adapted for tapered fitting with said conicalhatch, said hatch consisting in two parts divided along the parting lineof a seating groove for said O-ring, said parts constituting abimetallic hatch construction, and quick opening hatch dogs for saidhatch.